The long-term objective of this project is to improve devices and techniques for microwave tumor ablation and extend its application into new patient populations by optimizing system design and energy delivery in several tissue types. Microwave ablation is superior to currently available technologies in many respects: microwaves provide rapid volumetric heating, leading to more precise and complete treatments; microwave heating is less dependent on tissue properties, making it more suitable for emerging targets (e.g., lung and bone); and using multiple antennas improves treatment control, precision and efficacy. Unfortunately, current systems have failed to deliver on these promises and patients who could benefit from improved therapies have suffered. This proposal is based on the idea that understanding more about microwave tissue heating will facilitate development of optimized systems and techniques that will enhance patient benefit and expand the role of microwave ablation in cancer care. As microwave ablation systems begin to enter the marketplace, optimized treatment protocols will be required to enhance patient benefit and expand the role of microwave ablation in clinical cancer care. To this end, we propose to: 1) Create improved numerical models of tissue to more accurately predict device performance. Hypothesis: Accurate tissue models improve numerical simulations, easing design and treatment optimization. 2) Optimize antenna designs and power delivery for tissue-specific treatments Hypotheses: Antenna design and frequencies can be optimized for specific tissues or treatment targets. Applying high-power pulses will more rapidly coagulate tissue microvasculature to improve efficacy. When combined, these optimizations will create ablations 50% faster and 25% larger than current systems. 3) Develop multiple-antenna application techniques to optimize treatment speed and specificity. Hypotheses: Multiple-antenna techniques improve efficacy and precision, allowing more tailored treatments without increasing invasiveness. Ablations can be created by 50% faster and 40% larger than current systems. 4) Facilitate real-time adaptive power control by using integrated treatment monitoring Hypothesis: Treatment monitoring can be accomplished without imaging, using only the interstitial applicator. If successful, this project will advance knowledge of microwave tissue heating, and create innovative and unique approaches to power delivery that utilize all of the advantages that microwaves offer. These aims will substantially change clinical practice by increasing the size of tumors that can be treated with microwaves, further broadening the scope of microwave ablation to areas outside the liver and increasing the number of patients benefiting from minimally invasive treatments.